When the tide comes in acorn barnacles feed on drifting plankton. Their feathery legs beat through the water.

    Since these barnacles spend a great deal of time out of the water during low tides, they feed almost incessantly when the water returns. However, a touch or shadow causes the legs to retract in a flash into the shell which is then sealed by a double door.

Drawing by Iris Churcher MalaspinaUniversity-College

Phytoplankton

Drawing by Sir Alister Hardy. 1958. The Open Sea.